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Van Strien M.J.,Planning of Landscape and Urban Systems | Van Strien M.J.,Swiss Federal Institute of forest | Holderegger R.,Swiss Federal Institute of forest | Holderegger R.,ETH Zurich | And 2 more authors.

In landscape genetics, isolation-by-distance (IBD) is regarded as a baseline pattern that is obtained without additional effects of landscape elements on gene flow. However, the configuration of suitable habitat patches determines deme topology, which in turn should affect rates of gene flow. IBD patterns can be characterized either by monotonically increasing pairwise genetic differentiation (for example, F ST) with increasing interdeme geographic distance (case-I pattern) or by monotonically increasing pairwise genetic differentiation up to a certain geographical distance beyond which no correlation is detectable anymore (case-IV pattern). We investigated if landscape configuration influenced the rate at which a case-IV pattern changed to a case-I pattern. We also determined at what interdeme distance the highest correlation was measured between genetic differentiation and geographic distance and whether this distance corresponded to the maximum migration distance. We set up a population genetic simulation study and assessed the development of IBD patterns for several habitat configurations and maximum migration distances. We show that the rate and likelihood of the transition of case-IV to case-I F ST -distance relationships was strongly influenced by habitat configuration and maximum migration distance. We also found that the maximum correlation between genetic differentiation and geographic distance was not related to the maximum migration distance and was measured across all deme pairs in a case-I pattern and, for a case-IV pattern, at the distance where the F ST -distance curve flattens out. We argue that in landscape genetics, separate analyses should be performed to either assess IBD or the landscape effects on gene flow. © 2015 Macmillan Publishers Limited All rights reserved. Source

Gret-Regamey A.,Planning of Landscape and Urban Systems | Celio E.,Planning of Landscape and Urban Systems | Klein T.M.,Planning of Landscape and Urban Systems | Wissen Hayek U.,Planning of Landscape and Urban Systems
Landscape and Urban Planning

Given the accelerating rate of urbanization worldwide, the sustainable provision of urban ecosystem services becomes increasingly important for the growing number of city dwellers. Attempts to increase a single ecosystem service however often lead to reduction or losses of others. For making sound decisions about sustainable urban development, knowledge and awareness of the interactions between ecosystem services are thus necessary. In this paper, we show how interactive rulers embedded in a 3D GIS-based procedural modeling environment can assist in making urban ecosystem services trade-offs explicit for sustainable urban planning. The interactive rulers are slider bars that offer stakeholders the possibility to explore trade-offs in ecosystem services reflected in different urban designs. The approach is illustrated in a case study in Abu Dhabi, Masdar City, a new city designed from scratch. An interactive 3D visualization approach links parametric shape grammars for the design of generative urban patterns and the reporting of urban ecosystem services. We show how various urban design scenarios can be generated in an interactive manner allowing a balance between the esthetics of the urban designs and a set of indicators describing the provision of relevant ecosystem services. With this approach, the space for actions and behavioral alternatives become explicit - a crucial step for sustainable urban planning which calls for innovative strategies to adapt to these uncertain and rapid changes. © 2012 Elsevier B.V. Source

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